Remove IG name from all title tags

As part of the brand removal it needs to disapear from everywhere. This
is one such place.

https://www.pivotaltracker.com/story/show/48726949
Remove two more IG instances
Inside Government -> IG Admin in emails
Merge pull request #666 from alphagov/remove-ig-title

Remove Inside Government References

https://www.pivotaltracker.com/story/show/48726949